Invert level

The bottom of a pipe, trench, or tunnel

In civil engineering, the invert level is the base interior level of a pipe, trench or tunnel; it can be considered the "floor" level. The invert is an important datum for determining the functioning or flowline of a piping system. For example, the invert of a street sewer connection could affect the feasibility of adding a toilet in the basement of a house.

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